Romana Anulewicz-Ostrowska

ReI(CO)3+ complexes with N∩O− bidentate ligands

Simple reactions between Re(CO)5Cl and 2-benzoxazol-2-ylphenol, 2-benzothiazol-2-ylphenol or 2-(1-methyl-1H- benzoimidazol-2-yl)phenol (performed in boiling toluene) lead to dimeric complexes of general formula Re2(CO)6(N∩O−)2. The obtained dimeric species are quite stable in non-coordinating solvents, but in coordinating media (e.g., pyridine – pyr) they undergo disscociative solvolysis to form monomeric derivatives of general formula Re(CO)3(N∩O−)pyr. Molecular structures of both the dimeric and monomeric forms have been confirmed by means of X-ray measurements, electron impact mass spectrometry and IR spectroscopic investigations. UV-VIS absorption and emission properties of the newly synthesized Re(CO)3+ complexes have been investigated and briefly compared with those previously reported for their 8-oxyquinolinato analogues.

Synthesis of some halogenated tetraarylborates

The reactions of 3,4-dichlorophenylmagnesium bromide and 3,5-dichlorophenylmagnesium bromide with B(OEt) 3 and NaBF 4 were studied The corresponding tetraarylborates [(3,4-Cl 2 C 6 H 3 ) 4 B]NH 4 and [(3,5-Cl 2 C 6 H 3 ) 4 B]Na were obtained and characterized. The significant influence of the substituents inductive effect on the reaction course was revealed. NaBF 4 was found to be a valuable boron reagent in the synthesis of tetraarylborates containing highly electronegative substituents. The molecular structure of [(3-CF 3 C 6 H 4 ) 4 B]NH 4 obtained from the reaction of 3-trifluoromethylbromobenzene with NaBF 4 and Mg was determined using X-ray analysis.

Steric effects in alkylalane dioldiates [tBuAl(OC(CH3)2CH2C(CH3)2O)]2 a new (monoalkyl)alane O, O'-chelate complex

Abstract The dependence of the structure of alkylalane dioldiates on the steric bulk of the substituents on the aluminium, as well as steric hindrances of diol moiety is reported. Reactions of R3Al [where R=iBu, tBu] with 2,4-dimethylpentane-2,4-diol, butane-1,4-diol and propane-1,3-diol lead to the formation of alkylalane dioldiates, [tBuAl(OC(CH3)2CH2C(CH3)2O)]2 (1), iBu5Al3[(OC(CH3)2CH2C(CH3)2O)]2 (2) [tBu2Al(O(CH2)4OH)]2 (3), iBu5Al3(O(CH2)4O)2 (4) and tBu5Al3(O(CH2)3O)2 (5). The molecular structures of 1 and 3 have been determined by single crystal X-ray diffraction. In the reactions of iBu3Al with diols the trinuclear complexes of the general formula [R5Al3(diol(2H))2] (2 and 4) are formed irrespective of the diol moiety steric hindrances. tBu3Al reacts with diols to yield the products depending on the length of diol backbone and steric hindrances of the diol moiety. The interaction of the sterically crowded 2,4-dimethylpentane-2,4-diol with tBu3Al gives the new (monoalkyl)alane O,O′-chelate complex 1. In the case of unhindered aliphatic diols like butane-1,4-diol and propane-1,3-diol, the compound 3 with the strong intra-molecular hydrogen bonding interaction and the trimetallic compound 5 were obtained, respectively.

A new type of tetranuclear cyclopentadienylnickel cluster: synthesis and structural characterisation

Abstract A novel, 65-electron tetranuclear nickel cluster of the formula Cp3Ni4(CH3CCCH3)3 (6) was isolated and identified as the product of the reaction of nickelocene with methyllithium in the presence of 2-butyne at the molar ratio of reactants 1:1:1. The compound was fully characterised by spectroscopic and X-ray measurements. It crystallises from hexane in an orthorhombic crystal system and space group Pbcn. Corresponding unit cell parameters were determined as a=26.438(5), b=11.219(2), c=16.328(3) A; α=β=γ=90°; V=4843(2) A3; Z=8.

Reactions of methyl- and ethylaluminium compounds with alkoxyalcohols. The influence of alkoxyalcohol substituents on the structure of the complexes formed

Abstract Dimeric dimethylaluminium compounds {[Me 2 Al(μ-OCH 2 CH 2 O n Pr)] 2 ( 1 ), [Me 2 Al(μ-OCH(CH 3 )CH 2 O t Bu)] 2 ( 3 ), [Me 2 Al(μ-OCH 2 CH 2 CH 2 OEt)] 2 ( 5 ), [Me 2 Al(μ-OCH 2 CH 2 CH(Me)OMe)] 2 ( 7 ), [Me 2 Al(μ-OCH 2 CH 2 C(Me) 2 OMe)] 2 ( 9 )} and dichloroaluminium compounds {[Cl 2 Al(μ-OCH 2 CH 2 O n Pr)] 2 ( 2 ), [Cl 2 Al(μ-OCH(CH 3 )CH 2 O t Bu)] 2 ( 4 ), [Cl 2 Al(μ-OCH 2 CH 2 CH 2 OEt)] 2 ( 6 ), [Cl 2 Al(μ-OCH 2 CH 2 CH(Me)OMe)] 2 ( 8 ), [Cl 2 Al(μ-OCH 2 CH 2 C(Me) 2 OMe)] 2 ( 10 )} have been prepared. The molecular structures of compounds 2 , 3 , 6 , 8 , 9 and 10 have been determined by X-ray crystallography. All these compounds exist in the solid state as dimers with chelating ether-alkoxide ligands and five-coordinate aluminium atoms. Dichloroaluminium derivatives (compounds 2 , 4 , 6 , 8 and 10 ) exist as five-coordinate isomers also in solution, while dimethylaluminium ones (compounds 1 , 3 , 5 , 7 and 9 ) exist as an equilibrium mixture between four- and five-coordinate isomers. An increase of aluminium Lewis acidity in dichloroaluminium derivatives in comparison with dimethylaluminium ones results in substantial shortening of AlO distances. The R 2 Al⋯O (ether) R′ distance is mainly determined by the steric repulsion between the OR′ group and the two alkyl substituents on aluminium. The influence of electronic properties of R′ on Cl 2 Al⋯O (ether) R′ interaction was illustrated for compound 2 in comparison with literature data for analogous complexes.

Nature of the lowest triplet states of 4′-substituted N-phenylphenothiazine derivatives

The nature of the lowest triplet state of the donor–acceptor N-phenylphenothiazine derivatives has been studied by means of phosphorescence and EPR spectroscopy in various low temperature glasses. The triplet excitation of N-phenylphenothiazine and N-(p-anisyl)-phenothiazine is localised within the phenothiazine subunit. On the contrary, the 77 K phosphorescence of the molecules containing an electron acceptor group (i.e. –CN, –COCH3 or –COC6H5 at the 4′ position) is similar to that for benzonitrile, acetophenone or benzophenone, respectively, although the energy levels of their T1 states are higher than that of phenothiazine. With increasing temperature, however, their phosphorescence becomes similar to that characteristic for phenothiazine. This finding has been explained in terms of the excited-state intramolecular energy transfer accompanied by the planarisation of the phenothiazine kernel. The results of crystallographic investigations support this hypothesis.

Structure and biological activity of cationic [PtLCl(DMSO)]NO3·DMSO complex containing a chelated diaminosugar: methyl-3,4-diamino-2,3,4,6-tetradeoxy-α-l-lyxopyranoside

Cationic platinum(II) complex [Pt(C(7)H(16)N(2)O(2))(DMSO)Cl]NO(3).DMSO containing one chloride anion, methyl-3,4-diamino-2,3,4,6-tetradeoxy-alpha-L-lyxopyranoside (C(7)H(16)N(2)O(2)) and dimethylsulfoxide (DMSO) molecules forming a square-plane has been prepared and characterised, both spectroscopically and by single-crystal X-ray diffraction. Biological tests performed using leukemia L1210 cells have shown that toxicity of the title complex is similar to that of cisplatin.

Reactions of nickelocene with phenyl- and methyllithium in the presence of bis(trimethylsilyl)acetylene

Abstract Results of the reactions of nickelocene with phenyl- and methyllithium in the presence of bis(trimethylsilyl)acetylene have been reported. It was found that in the reaction of nickelocene with phenyllithium and bis(trimethylsilyl)acetylene three products were formed: di(cyclopentadienylnickel) complex with bis(trimethylsilyl)acetylene (NiCp)2(μ–η2–η2-Me3SiCCSiMe3) (1); di(cyclopentadienylnickel) complex with phenyl(trimethylsilyl)acetylene (NiCp)2(μ–η2–η2-PhCCSiMe3) (2) and tetra(cyclopentadienylnickel) complex with 1,4-bis(trimethylsilyl)-1,3-butadiyne (NiCp)4(μ,μ–η2–η2–η2–η2-Me3SiCCCCSiMe3) (3). Phenyl(trimethylsilyl)acetylene and 1,4-bis(trimethylsilyl)-1,3-butadiyne were the products of coupling and cross-coupling of {CpNiPh} and {CpNiCCSiMe3} formed as intermediate products of the reactions. All products were characterized by spectroscopic methods and crystal and molecular structures of compounds 1 and 3 were determined by single crystal X-ray measurements.

π-Electron delocalisation in the spacer of the O-H…N bridge in Schiff bases. Crystal and molecular structure of 3,5-dimethoxy-2 [(phenylimino) methyl]phenol and 4-methoxy-2-[(phenylimino) methyl] phenol

Abstract The spacer built up of NC, two CC, and CO bonds between the H-bond donating OH group and H-bond accepting nitrogen atom in the CN bond in Schiff bases exhibits a significant and strongly diversified degree of the π-electron delocalisation. No dependence between the delocalisation of π electrons and the H-bond strength is observed. The most important factor appears to be the mesomeric effect of the substituents attached to the ring of which a bond is a part of the spacer. This is supported by analysis of the geometry of 3,5-dimethoxy-2[(phenylimino) methyl] phenol and 4-methoxy-2-[(phenylimino) methyl] phenol presented in this study and molecular geometries of 47 well solved X-ray structures retrieved from the CSD. Delocalisation of π-electrons in the spacer of the H-bond depends chiefly on the substituent effect from the ring.

Structural studies of 4-aryloctahydro-pyrido[1,2-c]pyrimidine derivatives

Abstract 13C cross-polarisation magic angle spinning NMR data have been reported for four derivatives of 4-aryl-octahydro-pyrido[1,2-c]pyrimidine-1,3-dione and the X-ray diffraction data for two (with 2′-Me and 2′-OMe). The crystal structures show the presence of centrosymmetric cyclic dimers with intermolecular C1O⋯H–N or C3O⋯H–N hydrogen bonds, the configuration at the chiral centres (C4 and C4a) was determined as RR (SS). The twisting of aromatic ring at C4 with respect to the pyrido[1,2-c]pyrimidine skeleton is about 68–109°.